Prepaeation of effect threads



Patented May 8, i934 lTED STATES PATENT OFFICE 1,953,315 PREPARATION Oi EFFECT THREADS Alfred Rheiner, Basel, Switzerland, assignor to the firm Chemical -Works formerly Sandor,

Basel, Switzerland 1 Claim. (01. 3-20) in the specification of the U. S. Patent No. 1,861,320, filed June 16, 1927, a process for the production of efiect threads consisting of monoor diacetate of cellulose is described. According a to this specification .vegetable fibres in any form (loose material, yarns, woven fabrics, in a dry, moist, raw, bleached or dyed state) are left in anacetylating mixture consisting of acetic anhydride; glacial acetic acid and one of the cat-'- l alyzers as usually employed for the preparation of cellulose triacetate, only until the :desired monoor diacetylation is reached. As the acetylation proceeds under emission otheat and, as the acetylating mixtures as well as the vegetable fibres are bad. conductors of heat, with large charges local overheatings may occur, which might have the efiect that. the fibres in such places become hard and shrunk.

It has now been found that, to prevent an irregular acetylation, it is advantageous in such operation to keep the acetylation mixture or the fibres in movement. This precautionary measure is especially necessary, when threads in package form such as cops, cakes, "cheeses, warp threads g5 wound on beams and the like, are to be treated.

, The circulation of the acetylating mixture or the movement of the fibres in this mixture does not only prevent an irregular acetylation, but it further results in different unexpected advan- 39 tages.

The acetylation under circulation of the mixture can for instance becarried out at a much higher temperature, without increasing the risk of obtaining uneven results; this is especially desir- 5 able, if mixtures containing smaller quantities of acetic anhydride, are employed. The working with these mixtures is of a considerable economic importance. Acetic anhydride being the most expensive constituent of the mixture, it is obvious that the acetylation process becomes cheaper with mixtures containing as little anhydride as possible. Up to the present the working with such mixtures was considered to be impossible as well as the process described in the aforesaid 5 specification (see Hottenroth, Die Kunstseide 1926, page 354, lines 13-22). Contrary to this opinion it has been found that for instance cellulose monoacetate can be produced without difficulty with mixtures containing no more than the theoretically required quantity of acetic anhydride, if the acetylation is efiected at a somewhat increased temperature and whilst keeping the fibres in movement; furthermore the threads thus obtained possess an extraordinarily soft 555 tench.

,stituentsare subsequently added. The cellulose The acetylation in the above described manner can also be carried out with great advantage, if the cellulose material, instead of immersing same in an acetylation mixture consisting of acetic anhydride, glacial acetic acid and a catalyzer, is first 0 treated with one or two of the constituents of the mixture and the remaining constituent or conmaterial can thus first be placed in glacial acetic acid and the acetic anhydride and the catalyzers 5 added later, or it can first be impregnated with acetic anhydride and glacial acetic acid and the catalyzer added later. Moreover, the cellulose may first be impregnated with the catalyzer and the acetic anhydride and the glacial acetic acid 7 added later, or the fibres, which have been impregnated with the catalyzer, are introduced into a bath containing the mixture of acetic anhydride and glacial acetic acid.

Still other variations consist in introducing the cellulose material into a mixture of acetic anhydride and glacial acetic acid and adding the catalyst later or in introducing the cellulose fibres first either into a mixture of glacial acetic acid orof acetic anhydride and the catalyzer and adding the acetic anhydride, respectively the glacial acetic acid later.

Each of these methods can afiord satisfactory results when combined with suitable conditions of reaction. The circulation of the mixture is of great advantage as it allows of a quick mixing of the liquor and consequently or a uniform action on the fibres. v

The following examples illustrate the improved process, the parts being by weight.

Example 1 100 parts of kier-boiled cotton yarn are introduced into an acetylating mixture consisting of 30 parts of zinc chloride, 100 parts of acetic anhydride and 870 parts of glacial acetic acid of strength. The material is treated at 60 C. for about 10 hours whilst keeping the liquor in continuous circulation by means of a pump. Thereupon the yarn, which is unaltered in its structure, 100 is taken out and separatedirom' the mixture as completely as possible, washed and dried. The effect threads produced in this way remain practi-' cally uncolored in a dyebath containing substantive colours reserving acetate silk.

introduced into an acetylating mixture consisting of 40 parts of zinc chloride, 80 parts of acetic no anhydride and 880 parts of glacial acetic acid of 100% strength, so that the yarn is completely covered by the liquid. The bath is kept in regular circulation for 12 hours, whilst maintaining its temperature at 50 C. Thereafter the yarn is hydroextracted, washed and dried. 125 parts of a treated yarn are obtained, hardly distinguishable from the initial material as regards appearance, but which has no aflinity at all for substantive dyestufls.

Example} Example 4 100 parts of raw cotton yarn are introduced into a bath of 700 parts of 98% glacial acetic acid.

Aiter a short time 250 parts of acetic anhydride.

and 50 parts of'zinc chloride are added and the liquid kept in movement, at a temperature of 40 C., until a test, after washing and drying, can no longer be dyed with 1% Chloramine Sky blue FF (Colour Index of Dyers and Colorists, Bradford 1924, 1st edition, No. 518), which is the case after about 24 hours; Thereupon the yarn is sep arated from the liquor, washed and dried.

Example 5 100 parts of cops dyed with sulphur black T (said Colour Index, No. 978) and freed from any moisture are brought into a suitable vessel containing 800 parts of a mixture consisting of 10% of acetic anhydride, 3% of zinc chloride and 87% of glacial acetic acid 100%. After pumping through for 8 hours at 60 Qthe cops are hydroextracted, washed and dried. The black eflect threads thus prepared keep, in cross-dyeing with substantive dyestufis, their deep black shade.

Example 6 Cotton yarn dyed with Indanthrene blue GCD (said Colour Index, No. 1113) is transformed into dyed cellulose monoacetate by one of the processes described in the preceding examples. Although the glacial acetic acid is an excellent solvent for vat dyestuffs, the acetylating mixtures remain in spite of the continuous circulation, practically undyed.

'I'he'foregoing examples illustrate the use of zinc chloride as catalyzer. Obviously any other catalyzer used for the production of cellulose acetate, such as halogen hydroacids, nitric acid, phosphoric acid, halogenated fatty acids etc. may be employed whilst choosing the appropriate conditions of reaction.

What I claim is:

A process for the preparation of efiect threads,

having no afflnity for substantive dyestuffs and consisting of the lower acetylated derivatives of cellulose by the direct acetylation of cellulosic fibres without altering the original structure of such fibres, the reaction being efiected in a single bath and in a single operation by immersing natural cellulosic fibres in any form in an excess of an acetylating mixture maintained at a temperature between approximately 40 and 80 C. and consisting of acetic anhydride, glacial acetic acid and an acetylating catalyst, the fibres being entirely covered by and in contact with excess of acetylating mixture throughout the course of the reaction and allowing the acetylatingmixture to react on the fibres only until the monoand diacetylderivatives of cellulose have been formed, thereupon separating the resultant effect threads from the excess of acetylating mixture, said process being characterized in that the acetylating mixture does not contain more acetic anhydride than is theoretically necessary for the production of monoand diacetylderivatives of cellulose and in that during the acetylating operation a continuous relative movement is produced between the acetylating mixture and-the cellulose fibres.

' ALFRED RHEENER. 

